This invention relates to a transdermal drug delivery patch, in particular, a patch useful for the transdermal delivery of nicotine. The patch is useful in that it delivers an amount of nicotine which achieves a physiological effect, curbing the urge to smoke tobacco, and thus easing the physiological symptoms of nicotine withdrawal.
A long felt need has existed in the medical art for a transdermal nicotine patch. In the past, nicotine has been administered orally, for example by chewing a resin gum containing nicotine such as that sold commercially under the trade name NICORETTE.
Several transdermal nicotine products have recently been disclosed. One such transdermal delivery device is disclosed by Lohmann & Co. GmbH in WO 8801-516A, filed Aug. 28, 1986. Lohmann describes a controlled release transdermal delivery system with an active substance, e.g., nicotine, in a depot formed by a reservoir contained between an adhesive layer and a backing layer. A dispersion device is connected to the depot which is spatially defined from the matrix.
Von Tilly, Ger. Offen. DE No. 3,438,284 similarly discloses a nicotine-reservoir containing transdermal preparation which is alleged to deliver approximately 20 to 30 mg/day from a 10/20 cm.sup.2 patch.
Rose, et al. "Transdermal nicotine reduces cigarette craving and nicotine preference", Clin. Pharmacol. Ther., Vol. 38, No. 4, pp 450-456 (Oct., 1985) discloses that transdermal nicotine base (8 mg) applied in 30 percent aqueous solution under a polyethylene patch was helpful in reducing the urge to smoke tobacco.
It has been determined that a relatively constant nicotine blood level may help to curb the urge to smoke. Hence, one objective of the invention is to provide a transdermal nicotine patch which will deliver nicotine transdermally over an extended period of time, e.g., 16 to 24 hours. A further objective is to provide a transdermal nicotine patch which causes a minimum of local pruritis or discomfort where applied and worn on the skin.